1. Field of the Invention
The present invention relates to media independent handover (MIH), and particularly, to a method and device for transmitting communication link parameters.
2. Background of the Invention
Development of communication technology brings coexistence of various communication networks in a region, and current terminal devices can also support communication with more than one network, as shown in FIG. 1. Because different networks cover different service areas and have different service capabilities, user terminals may possibly be affected in the case of handover between different media networks, but it's desired to implement seamless handover between different media networks for mobile terminals to ensure the continuity of their services.
To satisfy the requirements for seamless handover of multimode terminals among different communication networks, an architecture in which a multimode terminal can implement a media independent handover service is proposed in the 802.21 protocol, as shown in FIG. 2. As defined in the protocol, a media independent handover layer (MIH layer) is added between the second layer (MAC layer) and the third layer (network layer) of the protocol stack of a network entity, in which interfaces for higher and lower layers of the protocol stack, a station management entity (SME), and an MIH entity of the same layer are defined to provide events, commands, and information services to implement the seamless handover between different media of the multimode terminal.
Some attributes of a lower layer link will affect different applications on a higher layer in different ways. For a device supporting media independent handover, either applications (MIH users) or end users of the device (device users) need to set some attribute parameters of the lower layer link to satisfy their respective requirements. Thus, the higher layer, as a layer of an application (an MIH user) and a direct interface layer between a device and users, needs to set or change some lower layer parameters, such as different link type identifiers, power supply operating modes of different media, and disable and activation symbols of different media links, so that the attributes of the lower layer may satisfy application requirements of higher layer users (MIH users) and device users.
To enable the higher layer to configure necessary link parameters of the lower layer, a current 802.21 draft provides a parameter configuration request primitive from the higher layer to the MIH layer, that is, MIH_Configure.request (a parameter configuration request), and a configuration response primitive from the MIH layer to the higher layer, that is, MIH_Configure.response (a parameter configuration response). FIG. 3 shows the configuration process.
The higher layer specifies one or more link parameters configured for the lower layer according to a set type parameter ConfigurationRequestsSets (a parameter set for requesting configuration) in the primitive MIH_Configure.request. After receiving a parameter configuration request sent from the higher layer, the MIH layer utilizes a command of configuring link parameters on the lower layer in an existing protocol (such as 802.11, 802.16, and 3GPP) to further send a link parameter configuration request to the lower layer. After the parameter configuration is performed, the lower layer uses the primitive responding to the configuration requests in an existing protocol (such as 802.11, 802.16, and 3GP) to return configuration results (successful, failed, or rejected) of each parameter in the parameter set for requesting configuration ConfigurationRequestSets to the MIH layer. The MIH layer further utilizes a parameter ResultCode (result code of the parameter configuration) in the primitive MIH_Configure.response to feed back the configuration result of the lower layer link parameter to the higher layer.
In the current 802.21 draft definitions for two primitives for a configuration request from the higher layer to the MIH layer and a request response from the MIH layer to the higher layer are as follows:
(1) Definition of the primitive MIH_Configure.request
MIH_Configure.request (SourceIdentifier,DestinationIdentifier,ConfigurationRequestsSets)NameTypeValid rangeDescriptionSourceIdentifierAny validThe identifier of entityIdentifierindividualwhere the request isor groupinitiated. This fieldidentifiermay be optionally leftempty if the commandis local.DestinationIdentifierMIH_LOCAL,The destinationIdentifierMIH_REMOTEidentifier of request orresponse. This is theidentifier of local orpeer MIH Function.Configura-Set ofN/AContaining a set oftionconfigurationconfigurationRequestparameters forparameters.Setscorrespondinginterfaces
(2) Definition of the primitive MIH_Configure.response
MIH_Configure.response (SourceIdentifier,DestinationIdentifier,ResultCode)NameTypeValid rangeDescriptionSourceIdentifierAny validThe identifier of entityIdentifierindividualwhere the request isor groupinitiated. This field mayidentifierbe optionally left empty ifthe command is local.DestinationIdentifierMIH_LOCAL,The destination identifierIdentifierMIH_REMOTEof request or response.This is the identifier oflocal or peer MIHFunction.ResultCodeEnumerateResult of trying to coniferthe link
According to the previous description, the parameter ResultCode adopted by MIH_Configure.response to feed back the link parameter configuration results for the lower layer to the higher layer is an enumeration-type parameter. The value of the parameter can only be one of successful, failed and rejected. That is to say, when the link parameters of the lower layer are configured by the higher layer, if some link parameters are configured successfully and others failed or are rejected, the MIH layer cannot feed back correct configuration results for different link parameters of the lower layer to the higher layer.